It is now well recoginzed that both the oral contraceptive "pill" and polymeric intrauterine devices (IUD) are effective means for controlling conception. Current research in these areas has been directed at decreasing the side effects associated with these methods. One method that has shown promise to accomplish this goal is the Uterine Progesterone System (UPS). However, the full advantages of this method have yet to be realized due to the lack of the biocompatibility of the polymers utilized and/or the lack of a suitable device which can deliver a truly constant release of the progestin from the UPS device. It is recognized by our group that a need exists for a combined biomaterials-pharmaceutical research effort in this area. It is the purpose of this project to study the basic mechanisms of diffusion of progestins through polymeric membranes, to investigate the effects of uterine fluids on the release of steroids from polymeric devices in vitro, to investigate several existing polymers and the newly developed poly HEMA (Hydrogel) membranes which may serve as suitable alternatives for polydimethyl siloxane in UPS devices, and to find a suitable drug formulation which will ensure the constant release of progestins encapsulated in polymeric materials.